Control apparatus



NOV. 12, 1940. p B LEONARD Re. 21,622

CONTROL APPARATUS Original Filed Aug. 5, 1936 5 ShetS-Sheet -l INVENTOR v4 3. ia/Wm;

BY W 29.1 ATTORNEY Nov. 12, 1940. P. B. LEONARD CONTROL APPARATUS Original Filed Aug. 5, 1936 3 Sheets-Sheet INVENTOR B04 8,Lo /Agp BY WM 4 F. 4M

' ATTORNEY 1940- P. B. LEONARD CONTROL APPARATUS Original Filed Aug. 5, 1956 3 Sheets-Sheet I5 ATTORNEY Reissued Nov. 12, 1940 CONTROL APPARATUS Paul B1 Leonard, Cuyahoga Falls, Ohio, assignor to Rance Incorporated, Columbus, Ohio, a corporation of Ohio Original No; 2,202,294, dated May 28, 1940, Serial No. 94,411, August 5, 1936. Application for re-- issue June 20, 1940, Serial No. 341,580

26 Claims.

My present invention relates to switches and more particularly to an electric switch.

One of the objects of my invention is to provide a switch in which the break," or separation, between the contacts is relatively wide in relation to the movement of the actuating mechanism.

Another object is to provide a constant, high, contact pressure at the instant before separation of the contacts, to eliminate chattering and subsequent arcing of the contacts. i

A further object is to provide a snap action dewce that operates through the resultant force components of opposing springs to produce positive snap action without the usual "graduating tendency.

Other and further objects and advantages will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of embodiment of the present invention is clearly shown.

Fig. 1 is a side elevational view of the switch;

Fig. 2 is a front elevational view of the switch having the housing cut away and the adjustment spring removed;

Fig. 3 is an enlarged front view of the snap mechanism;

Fig. 4 is an enlarged side view of the sim mechanism with the contacts in the closed position;

Fig. 5 is a similar view of Fig. 4-with the contacts in the open position;

Fig. 6 is a diagrammatic view of the mechanism in the closed position with spring 2| removed;

Fig. 7 is a view similar to Fig. '6 with spring 22 removed and spring 2| in place;

Fig. 8 is a diagrammatic view of the mechanism with spring 2| removed and shown in the position at the instant before the separation of the contacts;

Fig. 9 is a similar view to Fig. 8 with spring 22 removed and spring 2| in place;

Fig. 10 is a diagrammatic view of the mechanism with spring 2| removed and with the contacts in an open position, and,

Fig. 11 is a similar view to Fig. 10 with spring 22 removed and spring 2| in position.

The embodiment of the switch as shown in the drawings includes a frame or housing 2|). A base I9 supports a snap mechanism and a bellows housing I8. A bellows I1 is mounted within the housing I8.

The housing ID with the enclosed bellows I1 is rotatable when the switch is permanently mounted. To allow this movement, the housing It is provided with a flange. or abutment at its upper end, which is clamped to the base plate I9 by a removable collar I, held in place by screws 3|. This collar I does not clamp the housing I8 so tightly that it can not be turned manually, but neither is there any appreciable end play. This attachment allows rotation of the housing I8, together with the enclosed bellows II, without changing the relative position of the bellows 11 to' the associated mechanism. An elbow It or other convenient means is used to engageably attach the bellows I'I to the pressure system, which may be an air or steam line, or other type of conduit, or the bellows ma be connected to a bulb and tube as is familiarly used in refrigeration controls. A change of pressure within the bellows I'I acts to vary its length, which variation is transmitted to the snap mechanism by a push rod I5.

Rod I5 acts against a lever I I, which is U- shaped at the lower end, at the bearing point 32. The bearing 32 is formed by a depression in the lever M to receive the conical end of the rod I5. The lever I4 is the actuating lever for the switch mechanism and is pivoted at its lower end on the knife edge bearing of a rod 32, which in cross section resembles a sector of a circle. The rod 23 is set in apertures 26 formed in the bracket 5. These apertures 26 are of similar shape to the cross section of the rod 23. The bracket 5 is substantially U-shaped at its lower end and is permanently attached to the base plate I9. The bearings 36 in the actuating lever I4 area-lso in the shape of a sector of a circle, but with a greater degree are than is used in the bracket 5. This additional arc allows the necessary space for the movement of the lever I4 with respect to the bearing rod 23. The lever I4 is held tightly against the push rod I5 by the tension of a spring I3, attached to the lever I4 at 31 and adjustable through the screw I2 which turns in a plate 33. It will be noted that the plate 33 is provided with a projection 34 that is slidably engaged with a slot 35 in the frame 20. This engagement allows longitudinal adjustment of the plate '33 and attached spring I3 by the action of the screw I2, without the plate 33 turning, or otherwise becoming disengaged from the spring I3. The screw adjustment I2 varies the tension of the spring on the actuating lever I4 thereby changing the pressure exerted through the associated pin I5 on the bellows I I. This change in pressure varies the adjustment of the device. The projection 34 of plate 33 extends through frame 20, and is used as an indicator for the setting of the spring I3.

, ment II forms a knife edge which is pivoted on the lever l4 at the bearing 21. This construction may be more clearly seen in the enlarged views shown in Figs. 3, 4 and 5, where the relationship of parts is well illustrated.

The upper or free end of lever I4 is connected to the free end of a toggle, or flipper member 6 by the spring 2|. The toggle 6 is supported at its upper, pivoted end in a knife edge or V-shaped bearing 28 which is formed in the fixed bracket 5.. The lever II is also connected to the free end of the toggle 6 by the spring 22. The movement of the free end of the toggle 6 is limited and adjustable in both directions by the screw stops 3 and 4. Stop 3 is mounted on the lever I4; this particular construction is not limiting, but merely the most obvious method of manufacture. Stop 4 is screwed through the member 24 which is associated with the support bracket 5 by rivets. The screw 3 (see Fig. 3) is engaged through the threaded hole 8' in lever I4. This hole 3 is in the elongated spring slot which provides for a tight thread at all times without the use of a lock nut. Screw 4 is similarly engaged. These two stops 8 and 4 furnish the differential range adjustment for the instrument. It is evident that by limiting the free movement of the toggle 6 that the differential of the device may be varied within any reasonable limits.

The pivotal mounting of member II on lever I4 is important to the success of my invention.

As the lever I4 shifts in position, as occasioned by movement of the bellows II, the fulcrum 21 for lever II moves towards the dead center position of the toggle member 6 and the movable element I I. This action tends to reduce the bellows movement necessary to secure operation of the snap mechanism.

The pivotal mounting of lever II on lever I4 has another advantage from an electrical standpoint. As the lever I4 moves, its fulcrum point 21 also moves, but since this fulcrum point 21 is not on the same center as the fulcrum point 28,01 the lever I4, the fulcrum 21 described an are as it moves. This path of movement rubs, or wipes the contacts Ill against the contacts 8 which keep the surfaces of the contacts from sticking just before the separation of the contact:

' At the start of the closing cycle, the switch is position.

in the position shown in Fig. 5 with the projection 28 serving as a stop for the outward movement of lever II. As lever I4 moves to close the switch, due to a decrease in bellows pressure, the stop 28 on the lever I4 moves lever II clockwise so that it approaches its dead center This movement simultaneously displaces the spring 2I that is attached to the lever l4 and to the flipper 8. When spring 2| and fl pper 8 pass the dead center position, the spring 2| snaps the flipper 8 from stop I to stop 4; this movement also carries the spring 22 to the right of the dead center position for lever I I, and lever II will map from stop 29 to the contacts landtheswitchwillbeclosed.'Thissnapaction of lever II and flipper 8 is substantially instantaneous. At practically the same instant lever I4 will follow through, due to the change in pull of spring 2| caused by the change in the position of flipper 6 from stop 3 to stop 4, to hit against the lever II and greatly increase the closing contact pressure.

On opening the device, the spring 2I overcomes the spring 22 to snap the toggle open before the lever I4 contacts the projection 25 on lever II; neither is the point 29 in contact with the lever II. This allows for additional movement of free travel on the separation of the contacts. The projection 25 is placed on lever II to. engage lever I4 if'for any unforseen reason the contacts do not separate. This is an added measure of safety. In this event, the direct contact of the levers II and I4 cooperate to force the separation of the contacts. It will be noted that in this position the pressure within the bel lows is acting directly on the lever II through lever I4 without any intervening members being actuated. Similarly; on the closing of the device. the actuating member I4 through its integral projection 29, bears or acts directly on the movable member II. Thus, during closing of the switch, the action is direct from the bellows through lever I4 to the movable member I I without the intervening action of the toggle mechanism, which does not come into operation until this movable member I I passes its dead center position. At this point the flipper 6 is snapped through dead center to snap the movable member II to the closed position. It will be noted that the contact separation is relatively small at the instant before the closure of the contacts, whereas the contact separation is relatively great on the opening.. This relation between the contacts is very desirable as a wide break prevents arcing, etc., when the switch opens.

The leverage ratio of the actuating lever I4 is relatively high and may be utilized due to the construction of the switch, which does not have a graduating tendency at the instant before separation of the contacts but maintains the high contact pressure until the contacts are separated by the snap mechanism. Therefore, the movement of the upper end of the actuating lever I4 is relatively large compared to the movement of the lever or bellows end of the lever. Thus for a short bellows movement a wide separation of the contacts may be obtained.

The snap action of the device is acquired by the action of the two snap springs 2| and 22 cooperating with the movable contact lever II, the actuating lever I4, and the flipper 6. The spring 22 connects the movable contact member II to the flipper member 8. The tension of the a spring 22, through its horizontal component of force, tends to press the movable contacts III to the fixed contacts 8, in the closed position of the switch. The spring 2| connects the flipper 6 to the actuating member I4. The spring 2| is preferably heavier than the spring 22.

Figs. 6 to 11, inclusive, illustrate diagrammatically the, action of the springs and toggles as the switch is actuated for separation of the contacts. In Fig. 6 the contacts are shown in closed position, and for the sake of clarity, spring 2| is removed, since springs 2| and 22 superimpose on one another. in the side view of the switch. Fig. '7, therefore, is an identical view to Fig. but showin the spring 2| and omitting spring 22. Figs. 8 and 9 are similar views at the instant before separation of the contacts.

As the actuating member 4 moves counter clockwise from the position shown in Figs. 6 and 7, due to the expansion of the bellows, it displaces the spring 2| from the position shown in Fig. '7 to the position shown in Fig. 9. Although at the time lever |4 moves the spring 2| beyond its dead center position, with respect to flipper 6,. the flipper 6 is not displaced at that instant due to the opposing force of spring 22. At the instant; that the horizontal component of spring 2| exceeds the horizontal component of spring 22, the flipper will be snapped from the stop 4 to stop 3. Figs. 8 and 9 show the position of the elements at the instant that the force of spring 2| is equal to the force of spring 22. At the instant that the force of spring 2| overcomes the force of spring 22, the flipper 6 is snapped through its own dead center and the elements are moved from the position shown in Figs. 8 and 9 to the position shown in Figs. 10 and 11. Let us assume that the switch is in the position shown in Figs. 6 and 7 and, for example, spring 22 has a horizontal force component of ten pounds, the spring 2| having a horizontal force component of five pounds in the opposite direction. The resultant force component tending to keep the flipper 6 in its original position against stop 4, will be five pounds. As the spring 2| is displaced to the position shown in Fig. 9, its horizontal force component increases to a point where it is ten pounds in the opposite direction of the ten pound component of spring 22. This gives a resultant force of zero of the flippers against stop 4. v

The instant that the component of force of spring 2| exceeds ten pounds, it will snap the flipper 6 through the dead center position of the latter. Due to this movement of flipper 6, the angularity between the flipper 6 and the spring 2| is constantly increasing to produce a correspondingly constant increase in the horizontal force component of the spring 2|. stantly increasing component of force of spring 2| insures contact separation, which separation is constantly increasing in speed from the very start to the completion thereof.

The contact pressure of contact ID on contact 8 is unchanged until snap action occurs. Fig. 8

illustrates very clearly why the contacts have a maximum pressure even at the instant before separation, for it will be noted that the horizontal component force of spring 22 at its upper end as exerted on contacts I0 is unchanged during the movement of spring 2|.

The present switch presents a device with.

positive spring action to assure constant, high, contact pressures and positive make and break of the points, thus providing perfect switch operation, entirely devoid of chattering or arcing. The movable contacts Ill, due to very small differential range, but also allow an exceptional break, or movement of the points. This relatively large break is made possible by the "lost motion" and movable fulcrum features of the invention. In order that this "lost motion, which allows wider separation of contacts, does not increase-the difierential, the compensating movable fulcrum is provided for the movable contact member. The movement of the fulcrum points disposes the lever in position to snap with no additional travel of the bellows.

1 In other words the displacement of the fulcrum,

for the movable member, takes up the lost motion. Y

Although the description of my invention is directed to electrical switches, it is to be understood that the principles involved should not be limited to use in these specific devices. It is evident that the benefits derived from the described mechanism, namely, a relatively large movement of the snap member for a relatively small movement of the actuating medium, would be Well adapted for use in a number of devices completely divorced from electrical switches. The inherent advantages involved would, for example, be well employed in valves of the snap action type, for use with fluidsof various kinds, whether such valves or mechanisms are actuated by the described bellows or by such other well known mediums as bimetal, rod and tube expansion elements, etc.

In fact, the described mechanism will be extremely useful in any type of device where a strong, definite action or movement is, required under low difierential conditions.

While the form of embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

I claim as my invention:

1. In a snap action device, a movable element, a flipper fulcrumed at one end, a spring connecting the movable element and the flipper, an ac- This contuating member, a spring connecting the actuating member to the flipper, stop means disposed to contact the free end of the flipper and means or moving the actuating member.

2. In a snap acting device, relatively fixed and movable elements, a snap member, an elastic mean's cooperating with said movable element and said snap member, an actuating member, a resilient means connecting said actuating member and snap member, said snap member, resilient means' and actuating member having a dead center position, said actuating member being so disposed in relation to the snap member that when the dead center position of the snap member is passed that both the elastic means and the resilient means react cooperatively to move the movable element.

3. A snap acting device comprising, a movable element to be actuated, a flipper, a spring connecting the movable element and the flipper, an actuating member, a spring connecting the actuating member to said flipper and means for moving the actuating member.

4. A snap acting device comprising a movable element to be actuated;, a flipper fulcrumed at one end; a spring having one end thereof connected with the free end of the flipper and having the other end thereof connected with the element, said spring, flipper and element having a dead center position; an actuating member; a spring connected with the actuating member and with the free end of said flipper, said last spring, actuating member and flipper having a dead center position and said the first spring, flipper and first element when the second spring is moved beyond its dead center position relative to the flipper and actuating member; and means for moving the actuating member.

5. In a snap acting device, a movable element to be actuated, a flipper fulcrumed at one end; a spring having one end connected to the free end of the flipper and having the other end connected with the element, said spring, flipper and element having a dead center position, an actuating member carrying a fulcrum for said movable element; a second spring connected with the actuating member and flipper, said flipper, actuating member and spring having a dead center position, said actuating member being adapted to move the movable element and the second spring toward the dead center positions; and means for moving the actuating member.

6. In a snap acting device, a movable element to be actuated; a flipper fulcrumed at one end;

actuating member carrying a fulcrum for said movable element; a spring connected with the actuating member and with the free end of said flipper, said last spring, actuating member and flipper having a dead center position, said actuating member being adapted to move the movable element toward its dead center position, said last named spring being adapted to move the flipper beyond its dead center position with respect to the first spring, flipper and first element when the second spring is moved beyond its dead center position relative to the flipper and actuating member; and means for moving the actuating member.

'7. In a snap acting device, a movable element to be actuated; a flipper i'ulcrumed at one end; a spring having one end connected to the free end of the flipper and having the other end connected with the element; said spring, flipper and element having a dead center position; an actuating member carrying a fulcrum for said movable element; a spring connected with the actuating member and with the free end of said flipper, said last spring, actuating member and flipper having a dead center position, said actuating member being adapted to move the movable element toward its dead center position, said last named spring being adapted .to move the flipper beyond its dead center position with respect to the first spring, flipper and first element when the second spring is moved beyond its dead center position relative to the flipper and actuating member; and means for moving the actuating member.

8. In a snap acting device, relatively stationary and movable elements to be controlled; an actuating member, said movable element adapted to be limited in its movement in one direction by the stationary element and adapted to be limited in its movement in the other direction by the actuating member, said movable element and element when the spring, flipper, and movable element are moved beyond their dead center position; and a second spring connecting the flipper and the actuating member, said second spring, flipper and element having a dead center. position, said second spring being adapted to snap actuate the flipper beyond the dead center position of said first spring, flipper and movable element when the actuating member moves beyond its dead center position with respect to the flipper and second spring.

9. In a snap action device, a plurality of levers, yielding means interconnecting one of said levers to each of two other levers, said yielding means having unequal and opposing force components, means to actuate one of said second levers to increase the force components of one of said means whereby snap action occurs when the increasing force component exceeds the stationary force component of the other means.

10. In a snap acting device, a plurality oi. pivoted elements having their free ends disposed oppositely from one another, a spring connecting said elements for urging the free ends in one direction when the spring is in one position, a second spring connected to one of said elements for moving the elements in the opposite direction, and means for increasing the force of the second mentioned spring on the one element for overcoming the force of the first mentioned spring on the element.

11. In a snap acting device, a'movable element, resilient means for urging the element in a certain direction, said element and means being so disposed with respect to one another that the component of force of said means acting upon the element decreases when the element is moved in opposition to said means, a spring tending to move said element in a direction opposite the said certain direction, and means for moving the spring to increase the force of said spring to a point at which it overcomes the force of the first mentioned means.

12. In a snap acting device, a first movable member and a second movable member; a fixed support for the first movable member; anovercenter spring interconnecting the said movable members; an operating member; a fulcrum for said second movable member carried by the operating member; a spring interconnecting the operating member and said first movable mem ber for actuating the first movable member to move the first mentioned spring over dead center on movement of the operating member to cause snap action of the first and second movable members; and means for actuating the operating member.

13. In a snap acting device, a movable member; a snap member fulcrumed at a fixed point; elastic means cooperating with the movable member and the snap member, said movable member having a dead center position with respect to the elastic means and the snap member; an actuating member, said actuating member carrying said movable member; resilient means cooperating with the snap member and the actuating member, said actuating member causing said resilient means and said snap member to be moved past the dead center position of said movable member, elastic means and snap member for snap actuating the movable member.

14. In a snap acting device, an element movable between two extreme positions; a translatable resilient member for moving said element from one of the extreme positions to an opposite extreme position including a second resilient member for urging the first resilient member toward the second mentioned extreme position with respect to the element; and means for reversing the directions of force of the second resilient memberon the first member for moving said first member in opposite directions.

15. In a snap acting device, an element movable between two positions, said element having a pivot; a resilient member connected to the element for biasing said element in either of said positions, said member being movable to a position on either side of a. line through the pivot and the point of connection of the member and element; means, including a second resilient member, for yieldingly moving the first resilient member from one side of the said line to the other; and means for increasing the yielding effect of the second resilient member on the first member for moving said first member.

16. In a snap acting device, a movable element having a pivot; a spring connected to the element and being movable to a position on either side of a line through the pivot and the point of connection of the spring and element for actuating the element; means for moving the spring, including, a member connected to the spring and biased in one direction by the spring, and a second spring connected to the member for biasing the member in the opposite direction and means for moving the second spring relative to the nieinber'for increasing the biasing effect of the second spring whereby the member is moved in said opposite direction with a snap movement and moving the first spring therewith.

17. In a snap acting device, a movable element; means for limiting movement of the element between two positions; a translatable resilient member connected to the element; means for limiting movement of the resilient member between two positions; means for translating the resilient member for causing said element to be moved from one of its positions to the other, including, a second resilient member for urging the first mentioned resilient member from one of its said positions to the other; and means for reversing the directions of force of the second resilient member on the first member for moving the first member in either direction.

18. In a snap acting device, a movable element having translatable pivot; stop means for limiting movement of the element in one direction; snap mechanism for moving the element from the stop means, including a spring and a movable member, said spring connecting the element and the member and being disposed so that the moment of force thereof is at an angle with respect to a line from the pivot to the stop means to yieldingly urge the element against the stop means; an actuating member for moving the pivot to increase the angle between the spring and the said line while the actuating member moves in one direction; and means for shifting the spring to a position in which the moment of force thereof is opposite the pre-shifted position thereof for moving the element away from the stop means, said shifting means comprising snap acting mechanism including said movable member actuated by the actuating member after said actuating member moves a predetermined distance in said one direction.

19. In a snap acting device, a movable element; stop means for limiting movement of the element between two opposite positions; a spring connected to the element, said spring being adapted to move the element from one of said positions to the other; a second spring connected to the element for yieldingly retaining the element in either of said positions; and means for actuating the first spring for overcoming the yielding efiect of the second spring and move the element to the opposite position.

20. In a snap acting device, an element movable in two directions; a stop limiting the movement ofthe element in one of said directions and a stop limiting the movement of the element in the other of said directions; means formoving said element from one stop to the other with a snap movement; and means cooperating with said means for moving one of said stops relative to the other stop prior to snap movement of the element in the said one direction for increasing the snap movement of the element in the one direction and for moving said stop relative to the other stop prior to snap movement of the element in the said other direction by said snap means for decreasing the movement of the element in said other direction.

21. In a snap acting device, a pivoted element movable about its pivot in two directions; a stop limiting movement of the element'in one direction and a stop limiting movement of the element in the other'of said directions; snap acting means actuatable for moving said element from one stop to the other; and a member for actuating the snap acting means, said member being adapted to move one of said stops relative to the other of said stops in said one direction to increase the movement of said element by the snap acting means in said one direction and to move the said one stop relative to said other stop in the said other direction for decreasing the movement of the element by the snap acting means in said other direction.

22. In a snap acting device, a pivoted element movable in two directions; a stop limiting movement of the element about its pivot in one of said directions; a movable actuating member, said member having a part for engaging said element for limiting movement of the element in the other of said directions, said actuating memher, when moving, causing relative movement between said part and the stop; and snap mechanism operated by movement of said actuating member for moving said element to said limiting part and stop with a snap action.

the other of said stops for moving the pivoted element toward said other stop when saidmeans is operating the snap acting mechanism in a direction to move the element to said other stop.

24. In a snap acting device, a pivoted element movable in two directions; stops limiting the extent of movement of the element in said directions; snap mechanism for actuating the movable element; a lever carrying one of said stops; and means intermediate the stop and fulcrum of said lever for actuating the snap mechanism.

25. In a snap acting device, a lever movable in two directions; a stop for limiting movement of said lever in one direction; snap acting mechanism for actuating the lever including a lever and an overcenter spring connecting said levers; and means movable in one direction for moving the second mentioned lever for imparting, through the spring, snap acting movement to the first mentioned lever away from the stop, said means being movable in the opposite direction for moving the second mentioned lever for imparting, through the spring, snap acting movement of the first mentioned lever toward the stop, said means having a part engagable with the first mentioned lever, said means, when moving, causing relative movement between said part and the stop for moving said first mentioned lever toward the stop while said means is moving in said opposite direction and before the second mentioned lever is moved sufficiently to impart the second mentioned snap acting movement.

26. In a snap acting device, a lever movable in two directions; a stop for limiting movement of said lever in one direction; snap mechanism for actuating the lever including a movable member and an overcenter spring connecting the lever and movable member; means movable in one direction for moving the movable member for imparting, through the spring, snap movement to the lever away from the stop, said means being movable in the opposite direction for moving the movable member for imparting, through the spring, snap acting movement to the lever toward the stop; and means movable, relative to said stop, by the first mentioned means and engageable with the lever for moving the lever toward the stop while the first said means is moving in said opposite direction and before the movable member is moved sufliciently to impart the second mentioned snap acting movement.

PAUL B. LEONARD.- 

